miércoles, 5 de junio de 2013

Mediterran​ean diet slows atheroscle​rosis progressio​n in PREDIMED

Lyon, France - High adherence to a Mediterranean diet appears to slow the progression of carotid plaque, a PREDIMED substudy suggests. Of note, investigators found an attenuation of plaque progression in the Mediterranean diet arm of the study that included supplementation with nuts and no such change in the other intervention arm, which included supplemental extra virgin olive oil.

Dr Aleix Sala-Vila

This difference, however, may simply have been a product of limited sample size, Dr Aleix Sala-Vila (Institut d'Investigacions Biomèdiques August Pi Sunyer, Barcelona, Spain) said here today at the European Atherosclerosis Society (EAS) 2013 Congress.

As previously reported by heartwire, PREDIMED was a large primary-prevention trial that randomized 7447 patients at high CV risk (but no CVD) to a control diet (including advice to reduce dietary fat) or Mediterranean diet (MedDiet) supplemented with extra virgin olive oil or mixed nuts (walnuts, almonds, and hazelnuts). After 4.8 years, the risk of major CV events (MI, stroke, death from CV causes) was reduced by 30% in the Mediterranean groups combined, compared with the control diet. The Mediterranean diet group assigned to the extra virgin olive oil supplementation saw a 30% reduction, while those in the nut supplementation group saw a 28% reduction, both compared with the control group.

In their latest analysis, Sala-Vila and colleagues looked at plaque volume and mean and maximum internal carotid-artery intima-media thickness (ICA-IMT). ICA-IMT, Sala-Vila explained to heartwire, may be a better indication of subclinical atherosclerosis and more predictive of CVD than measurements of common carotid-artery IMT.

Imaging insights

A total of 61 patients in the control group, 57 in the MedDiet plus supplementary olive-oil group, and 46 in the MedDiet plus nuts group underwent carotid ultrasound imaging at baseline and after a minimum of two years on their assigned diet.

After controlling for duration of time on the diet and changes in use or dose of statins, investigators saw a significant reduction in carotid plaque in the combined MedDiet group and MedDiet-plus-nuts group, but not in the MedDiet-plus-olive-oil group. A similar pattern was seen in both mean and maximum ICA-IMT.

Measurement

Control (low-fat diet)

MedDiet plus olive oil

MedDiet plus nuts

Combined MedDiet

Plaque volume (maximum, mm3)

+0.137

+0.044

-0.086*

-0.013*

ICA-IMT (mean, mm)

+0.049

-0.006

-0.076*

-0.037*

ICA-IMT (maximum, mm)

+0.177

+0.032

-0.023*

+0.008*

ICA-IMT=internal carotid artery intima-medial thickness

*p<0 .05="" control="" vs="">

Speaking with heartwire, Sala-Vila was careful to point out the shortcomings of sonography for understanding plaque progression. But in a before-and-after example in his presentation, he showed that the width and apparent makeup of the plaque also changed over time.

"All we can say is that we saw regression of the volume of the plaque, that's it. But if you look here [at the baseline images], you can see an area of shadow that suggests lipid core, and over time, this shadow turns white—this typically means less lipid and more calcium, and this points to a more stable plaque."

The ICA-IMT results "can help explain, in part, the cardioprotective effects afforded by these types of foods, which are typical of the Mediterranean diet," Sala-Vila concluded.

Meaningful change?

Dr Emilio Ros

Also discussing the changes, senior author Dr Emilio Ros (Institut d'Investigacions Biomèdiques August Pi Sunyer) agreed that the changes in ICA-IMT were suggestive of the plaque progressing from lipid-rich to fibrous but that further insights will come from an MRI study now under way in the PREDIMED cohort.

He also noted that the changes reported, although small, are likely "meaningful" changes.

"Atherosclerosis always progresses, as you can see in the control group," Ros said. On IMT, this progression is typically in the range of 0.02 mm per year, he noted. "So what we can say is, there is progression in the control group, there is delayed progression in the olive-oil group, and there is a slight regression in the nuts group."